Estimation of land surface temperature and emissivity from AMSR-E data

Abstract

A radiative transfer model to compute brightness temperatures in the microwave region for the soil-vegetation- atmosphere system has been developed in this study. Considering the various atmospheric conditions, a microwave brightness temperature database is generated for a wide range of surface dielectric constant and roughness properties under AMSR-E sensor configurations by using the soil-vegetation-atmosphere radiative transfer model. From the land surface emissivities in the simulated database, the linear relationships of surface emissivities between different channels for the advanced microwave scanning radiometer-earth observing system (AMSR-E) are established in this study. The analysis of the stability and the root-mean-square error (RMSE) for these linear relations indicates that the relationship using three channels is the best of all. The cloud-free AMSR-E actual satellite microwave data combining with MODIS land surface temperature product are used to validate these relationships. The linear relationship derived from the simulated database is in agreement with that from AMSR-E data. This emissivity model as a constrain condition of the radiative transfer equation is applied to retrieval LST and emissivity, and the RMSE of the results is lower than 1 K for LST, 0.0025 for emissivity. So the relationships of emissivity between different channels are very useful to derive land surface parameters directly from AMSR-E data, which will promote the application of AMSR-E data in many fields, such as climate, hydrology, and ecology.